Conventional gas-turbine engine blades are made of metal, such as titanium. Fan blades, of this type, are capable of withstanding the temperatures to which they are exposed, erosion resistance and have a relatively good chance of surviving impact with foreign bodies, such as bird strikes, without seriously affecting engine performance. Metal blades, however, are relatively heavy and so increase the overall weight of the engine and reduce its performance. Efforts have been made, therefore, in recent years to develop blades made of alternative, lighter materials such as composite materials, for example, carbon fiber epoxy composites. The problem with such composite blades is that they are not as robust as metal blades and are more easily damaged by contact with foreign objects. Attempts have been made to protect the leading edge of the blades, which are most likely to be subject to damage, by means of metal sheaths. Examples of composite blades are described in, U.S. Pat. Nos. 5,881,972 and 7,896,619.
Accordingly, there is a need to provide an improved blade for gas turbine engines.